Method of head stack assembly flexible circuit assembly attached to an actuator arm

ABSTRACT

A method for mounting a head stack assembly (HSA) circuit assembly is disclosed. A flexible circuit substrate may be coupled to a stiffener. The stiffener may be a metal, such as aluminum, or some other stiff and durable material. The flexible circuit substrate may be made of an organic material and may have a series of electronic leads embedded in the flexible circuit substrate. The flexible substrate may be coupled to the stiffener by an adhesive or laminated onto the stiffener. The stiffener may be mounted onto the actuator arm by soldering or by laser welding.

BACKGROUND INFORMATION

The present invention relates to magnetic hard disk drives. Morespecifically, the present invention relates to a method of assemblingactuator driving mechanisms.

In the art today, different methods are utilized to improve recordingdensity of hard disk drives. FIG. 1 provides an illustration of atypical disk drive. The typical disk drive has a head gimbal assembly(HGA) configured to read from and write to a magnetic hard disk 101. TheHGA and the magnetic hard disk 101 are mounted to the base 102 of a mainboard 103. The disk 101 is rotated relative to the base 102 by a spindlemotor 104. The HGA typically includes an actuator arm 105 and a loadbeam 106. The HGA supports and positions a magnetic read/write slider107 above the magnetic hard disk 101. The slider may contain transducersto perform the read/write function. The HGA is rotated relative to thebase 102 along the axis of a pivot bearing assembly 108 by an actuatorframe 109. The actuator frame 109 contains an actuator coil 110 drivenby a magnet 111. A relay flexible printed circuit 112 connects a boardunit 113 to the transducer of the magnetic read/write slider 107. Thesignal from the transducer is amplified by the preamplifier 114 beforebeing transmitted along the relay flexible printed circuit.

The relay flexible printed circuit 112 may be attached by pin soldering.However, the “flux” that is essential for this pin soldering causes acouple of problems. First, the cleaning process must be immediatelyimplemented to remove the flux with soldering. Next, the tin containedin the solder causes pollution of the contacts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides an illustration of a typical disk drive.

FIG. 2 provides an illustration of one embodiment of a head stackassembly with a flexible circuit substrate.

FIG. 3 provides a cross-section illustration of one embodiment of themounting of the flexible circuit substrate on the actuator arm.

FIG. 4 provides an illustration of an alternate embodiment of a headstack assembly with a flexible circuit substrate.

FIG. 5 provides a cross-section illustration of the alternate embodimentof the mounting of the flexible circuit substrate on the actuator arm.

DETAILED DESCRIPTION

A method for mounting a head stack assembly (HSA) circuit assembly isdisclosed. In one embodiment, a flexible circuit substrate may becoupled to a stiffener. The stiffener may be a metal, such as aluminum,or some other stiff and durable material. The flexible circuit substratemay be made of an organic material and may have a series of electronicleads embedded in the flexible circuit substrate. The flexible substratemay be coupled to the stiffener by an adhesive or laminated onto thestiffener. The stiffener may be mounted onto the actuator arm bysoldering or by laser welding.

FIG. 2 provides an illustration of one embodiment of a head stackassembly with a flexible circuit substrate 201. A plurality of headgimbal assemblies may be coupled to the pivot bearing assembly 108. Asuspension flexible circuit trace 202 may be attached to each load beam106 and actuator arm 105, and may run from a transducer of each slider107 to a single flexible circuit substrate 201. The flexible circuitsubstrate 201 may be made from an organic material. The actuator arm maybe made of aluminum and manufactured by machining. The flexible circuitsubstrate 201 may be a substrate with a number of bond pads and apreamplifier chip 114 for signal processing. Each set of bond pads maybe associated with a suspension flexible circuit trace 202. One or moreleads running from the bond pads to the preamplifier 114 may be embeddedin the flexible circuit substrate 201. The suspension flexible circuittrace 202 may be placed over these bonding pads on the flexible circuitsubstrate 201 to be electrically coupled to the flexible circuitsubstrate 201. To accomplish this, the termination pad of suspensionflexible circuit trace 202 may be bonded to the corresponding bond padon the flexible circuit substrate 201. For example, soldering orultrasonic bonding may be used to connect the suspension flexiblecircuit trace 202 to the bond pads on the flexible circuit substrate 201for a head stack assembly (HSA). One or more location pins 203 may beused to solder the flexible circuit substrate 201 in place. The locationpins 203 would extend from the actuator arm 105 up through the flexiblecircuit substrate 201. The flexible circuit substrate 201 may beconnected to a control circuit 112 by a flexible circuit assembly 111.In addition to controlling the read/write functions of the transducer ofthe slider 107, the control circuit 112 may also control the movement ofthe actuator frame 109.

FIG. 3 provides a cross-section illustration of one embodiment of themounting of the flexible circuit substrate 201 on the actuator arm 105.The flexible circuit substrate 201 may be coupled to a stiffener 301that facilitates mounting the flexible circuit substrate 201 to theactuator arm 105. The stiffener 301 may be made of aluminum, or someother durable material or metal. The flexible circuit substrate 201 maybe coupled to the stiffener 301 using an adhesive, such as an epoxy. Thepreamplifier 114 and the suspension flexible circuit trace 202 bond pads302 may be coupled to the flexible circuit substrate 201. One or morelocation pins 203 may extend up from the actuator arm 105 through thestiffener 301 and the flexible circuit substrate 201. The location pins203 may be made from metal and mounted on the actuator arm 105 bypress-fitting. The stiffener 301 and the flexible circuit substrate 201may be then coupled to the location pins 203 by applying a solder ball303 and soldering the stiffener 301 and flexible circuit substrate 201in place.

FIG. 4 provides an illustration of an alternate embodiment of a headstack assembly with a flexible circuit substrate 201. In thisembodiment, the flexible circuit substrate 201 and stiffener 301 may bemounted on the actuator arm 105 using laser welding. The stiffener 301may be laser welded to the actuator arm 105 at one or more points 401.

FIG. 5 provides a cross-section illustration of the alternate embodimentof the mounting of the flexible circuit substrate 201 on the actuatorarm 105. The flexible circuit substrate 201 and the stiffener 301 may bepreliminarily combined with an adhesive and forms a laminationstructure. Electrical elements 501 and bonding pads 302 may be added tothe flexible circuit substrate 201 during the lamination process. TheHSA circuit assembly may be aligned and then fixated onto the plane ofan actuator arm. One laser beam may be applied to the metal stiffenerfor a predetermined period of time to make the specific welding spot 401between the stiffener 301 and flexible circuit substrate 201. Thewelding spots 401 may be produced by melting the metal stiffener 301 andactuator arm 105 by some means of concentrated heat energy, producing afairly clean, non-contaminated connection. Good reliability and highbonding strength is achieved with this mounting operation, probablyrequiring no further cleaning. The welding spots 401 may be arranged onthe metal stiffener 301 according to the needs and structure of specificHSA.

Although several embodiments are specifically illustrated and describedherein, it will be appreciated that modifications and variations of thepresent invention are covered by the above teachings and within thepurview of the appended claims without departing from the spirit andintended scope of the invention.

1. A head stack assembly (HSA) circuit assembly, comprising: at leastone actuator pad to be electrically coupled to a printed circuit board;a flexible circuit substrate to electrically couple a slider to the atleast one actuator pad; and a stiffener to be mounted between theflexible circuit substrate and an actuator arm.
 2. The HSA circuitassembly of claim 1, wherein the stiffener is made of aluminum.
 3. TheHSA circuit assembly of claim 1, wherein the flexible circuit substrateis made of an organic material.
 4. The HSA circuit assembly of claim 3,wherein the flexible circuit substrate has at least one embedded leadconnecting the slider to the at least one actuator pad.
 5. The HSAcircuit assembly of claim 1, wherein the flexible circuit substrate iscoupled to the stiffener with an adhesive.
 6. The HSA circuit assemblyof claim 1, wherein the stiffener is mounted to the actuator bysoldering at least one pin extending from the actuator arm through thestiffener and the flexible substrate.
 7. The flexible circuit assemblyof claim 1, wherein the stiffener is mounted to the actuator by laserwelding the stiffener to the actuator arm.
 8. A head stack assembly,comprising: an actuator arm to place a slider above a magnetic storagemedium; a printed circuit board to control the slider and the actuatorarm; and a flexible circuit assembly, including: at least one actuatorpads to be electrically coupled to a printed circuit board; a flexiblecircuit substrate to electrically couple a slider to the at least oneactuator pad; and a stiffener to be mounted between the flexible circuitsubstrate and an actuator arm.
 9. The head stack assembly of claim 8,wherein the stiffener is made of aluminum.
 10. The head stack assemblyof claim 8, wherein the flexible circuit substrate is made of an organicmaterial.
 11. The head stack assembly of claim 10, wherein the flexiblecircuit substrate has at least one embedded lead connecting the sliderto the at least one actuator pad.
 12. The head stack assembly of claim8, wherein the flexible circuit substrate is coupled to the stiffenerwith an adhesive.
 13. The head stack assembly of claim 8, furthercomprising at least one pin extending from the actuator arm through thestiffener to be soldered to the stiffener.
 14. The head stack assemblyof claim 8, wherein the stiffener is mounted to the actuator by laserwelding the stiffener to the actuator arm.
 15. A hard disk drive,comprising: a magnetic storage medium to store data; a base to supportthe magnetic storage medium; an actuator arm to place a slider above amagnetic storage medium; a pivot to move the actuator arm in relation tothe magnetic storage medium; a printed circuit board to control theslider and the actuator arm; and a flexible circuit assembly, including:at least one actuator pad to be electrically coupled to a printedcircuit board; a flexible circuit substrate to electrically couple aslider to the at least one actuator pad; and a stiffener to be mountedbetween the flexible circuit substrate and an actuator arm.
 16. The harddisk drive of claim 15, wherein the stiffener is made of aluminum. 17.The hard disk drive of claim 15, wherein the flexible circuit substrateis made of an organic material.
 18. The hard disk drive of claim 17,wherein the flexible circuit substrate has at least one embedded leadconnecting the slider to the at least one actuator pad.
 19. The harddisk drive of claim 15, wherein the flexible circuit substrate iscoupled to the stiffener with an adhesive.
 20. The hard disk drive ofclaim 15, further comprising at least one pin extending from theactuator arm through the stiffener to be soldered to the stiffener. 21.The hard disk drive of claim 15, wherein the stiffener is mounted to theactuator by laser welding the stiffener to the actuator arm.
 22. Amethod, comprising: electrically coupling a slider to at least oneactuator pad with a flexible circuit substrate; and mounting theflexible circuit substrate to an actuator arm with a stiffener betweenthe flexible circuit substrate and the actuator arm.
 23. The method ofclaim 22, wherein the stiffener is made of aluminum.
 24. The method ofclaim 22, wherein the flexible circuit substrate is made of an organicmaterial.
 25. The method of claim 24, wherein the flexible circuitsubstrate has at least one embedded lead connecting the slider to the atleast one actuator pad.
 26. The method of claim 22, further comprisingcoupling the flexible circuit substrate to the stiffener with anadhesive.
 27. The method of claim 22, further comprising mounting thestiffener to the actuator by soldering at least one pin extending fromthe actuator arm through the stiffener and the flexible substrate. 28.The method of claim 22, further comprising mounting the stiffener to theactuator by laser welding the stiffener to the actuator arm.